Replacement heart valve, valve holder and methods of making same

ABSTRACT

A replacement heart valve device usable in a medical procedure in relation in heart valve replacement of a patient. In one embodiment, the replacement heart valve device includes a heart valve holder or conduit holder formed in the form of a cylindrical tube having a longitudinal cut substantially extending from one end to the other end of the cylindrical tube, and a conduit formed with a tubular segment of an elastic material. The conduit is mountable onto the heart valve holder or conduit holder or self-expanding stent. In one embodiment, at least a portion of the conduit is formed with a single layer of the elastic material. In another embodiment, at least a portion of the conduit is formed with two layers of the elastic material.

CROSS-REFERENCE TO RELATED PATENT APPLICATION

This application claims the benefit, pursuant to 35 U.S.C. §119(e), ofU.S. provisional patent application Ser. No. 60/925,822, filed Apr. 23,2007, entitled “REPLACEMENT HEART VALVE, VALVE HOLDER AND METHODS OFMAKING AND USING SAME,” by Megumi Mathison, which is incorporated hereinby reference in its entirety.

FIELD OF THE INVENTION

This invention relates to a replacement heart valve, and moreparticularly relates to a replacement heart valve formed with a tubularsegment of an elastic material for replacement of a defective heartvalve of a human or animal.

BACKGROUND OF THE INVENTION

There are four valves in the heart that serve to direct blood flowthrough the two sides of the heart. On the left (systemic) side of theheart are: (1) the mitral valve, located between the left atrium and theleft ventricle, and (2) the aortic valve, located between the leftventricle and the aorta. These two heart valves direct oxygenated bloodfrom the lungs through the left side of the heart and into the aorta fordistribution to the body. On the right (pulmonary) side of the heartare: (1) the tricuspid valve, located between the right atrium and theright ventricle, and (2) the pulmonary valve, located between the nightventricle and the pulmonary artery. These two heart valves directde-oxygenated blood from the body through the right side of the heartand into the pulmonary artery for distribution to the lungs, where theblood becomes re-oxygenated in order to begin the circuit anew.

All four of these heart valves are passive structures in that they donot themselves expend any energy and do not perform any activecontractile function. They consist of moveable “leaflets” that open andclose in response to differential pressures on either side of the valve.The mitral and tricuspid valves are referred to as “atrioventricularvalves” because they are situated between an atrium and ventricle oneach side of the heart. The mitral valve has two leaflets and thetricuspid valve has three. The aortic and pulmonary valves are referredto as “semilunar valves” because of the unique appearance of theirleaflets, which are shaped somewhat like a half-moon and are more aptlytermed “cusps”. The aortic and pulmonary valves each have three cusps.

Heart valves may exhibit abnormal anatomy and function as a result ofcongenital or acquired valve disease. Congenital valve abnormalities maybe well-tolerated for many years only to develop a life-threateningproblem in an elderly patient, or may be so severe that emergencysurgery is required within the first few hours of life. Acquired valvedisease may result from causes such as rheumatic fever, degenerativedisorders of the valve tissue, bacterial or fungal infections, andtrauma.

Since heart valves are passive structures that simply open and close inresponse to differential pressures on either side of the particularvalve, the problems that can develop with heart valves can be classifiedinto two categories: (1) stenosis, in which a valve does not openproperly, and (2) insufficiency (also called regurgitation), in which avalve does not close properly. Stenosis and insufficiency may occurconcomitantly in the same valve or in different valves. Both of theseabnormalities increase the workload placed on the heart. The severity ofthis increased stress on the heart and the patient, and the heart'sability to adapt to it, determine whether the abnormal valve will haveto be surgically replaced (or, in some cases, repaired).

Valve repair and valve replacement surgery is described and illustratedin numerous books and articles, and a number of options, includingartificial mechanical valves and artificial tissue valves, are currentlyavailable. However, the currently available options cannot duplicate theadvantages of native (natural) heart valves. Some of the availablemechanical valves tend to be very durable, but are problematic in thatthey are thrombogenic and exhibit relatively poor hemodynamicproperties. Some of the available artificial tissue valves may haverelatively low thrombogenicity, but lack durability. Additionally, eventhese artificial tissue valves often do not exhibit hemodynamicproperties that approach the advantageous hemodynamic performance of anative valve. Some artificial tissue valves attempt to copy the form ofnative heart valves. Such artificial tissue valves still fall short indurability and in hemodynamic performance.

Moreover, external valve conduits for right ventricular outflow tract(RVOT) have markedly extended the range of complex congenital heartdefects that can be repaired: pulmonary atresia, complex tetralogy ofFallot, double outlet right or left ventricle with pulmonary stenosis,truncus arteriosus, transposition of great arteries with ventricularseptal defect and pulmonary stenosis, and other complex forms ofcongenital heart disease.

Although the immediate and long-term survival of patients is gratifying,all conduits deteriorate, requiring the need to have close, constantfollow-up. A large proportion, if not all, will have to be replaced atleast once during the patient's lifetime. In the case of children,multiple surgeries are often required, which put the child at risk andcan be physically and emotionally draining for the child and his or herfamily. The development and use of improved substitutes for RVOTconduits could reduce the need for multiple surgeries for children withvarious congenital heart diseases. Tissue-engineered RVOT conduits couldsignificantly improve the quality of life for such children whiledecreasing the associated medical costs.

Therefore, a heretofore unaddressed need still exists in the art toaddress the aforementioned deficiencies and inadequacies.

SUMMARY OF THE INVENTION

The present invention, in one aspect, relates to a method of making areplacement heart valve that is implantable to a patient. In oneembodiment, the method has the step of providing a tubular segment of anelastic material having a first end portion and an opposite, second endportion, an interior surface, an exterior surface and a diameter d₁. Theelastic material is one of an intestinal tissue obtained from amammalian abdomen, a man-made bio-compatible tissue, and a polymericmaterial. For example, the intestinal tissue can be extracted from thepatient who receives the replacement heart valve. Alternatively, theintestinal tissue can be extracted from other human beings and/oranimals.

The method also has the steps of folding the first end portioninside-out towards to the second end portion such that the first end ofthe tubular segment reaches a position on the exterior surface and thetubular segment has a new first end, where the first end and the newfirst end define a new first end portion with an axial distance d₂ thatis substantially equals to d₁, and forming a plurality of cusps on thenew first end portion axially. In one embodiment, the step of forming aplurality of cusps on the new first end portion axially has the step offorming three cusps by sewing along three lines on the new first endportion longitudinally, where the three cusps are formed substantiallyparallel to each other and substantially apart from each other in 120°,as seen from a longitudinal, central axis of the tubular segment. Thesewing in one embodiment is performed with one or more threads of 7-0 or6-0 prolene.

Furthermore, the method has the steps of inverting the tubular segmentinside out so that the exterior surface of the tubular segment and theinterior surface of the tubular segment exchange their geometricpositions to form a replacement heart valve that has a conduit at leastpartially with a single layer of the elastic material. Moreover, themethod can be practiced to create a replacement heart valve that has aconduit at least partially with two layers of the elastic material fromthe replacement heart valve that has a conduit at least partially with asingle layer of the elastic material. In one embodiment, the second endportion is folded inside-out towards to the new first end such that thesecond end of the tubular segment substantially reaches the new firstend. As a result, a conduit at least partially with two layers of theelastic material is formed with the new first end and a new second end,where the new first end and the new second end define an axial distanced₃ that is no smaller than either of d₁ and d₂.

In operation, each of a replacement heart valve that has a conduit atleast partially with a single layer of the elastic material and aconduit at least partially with two layers of the elastic material canbe mounted onto a heart valve holder or conduit holder.

In another aspect, the present invention relates to a replacement heartvalve made according to the method as disclosed above.

In yet another aspect, the present invention relates to a replacementheart valve implantable in a patient. In one embodiment, a replacementheart valve includes a conduit formed with a tubular segment of anelastic material, wherein the conduit has a first end portion and anopposite, second end portion, and a plurality of cusps formed axiallyextending inwardly from one of the first and second end portions. In oneembodiment, the conduit is formed at least partially with a single layerof the elastic material. In another embodiment, the conduit is formed atleast partially with two layers of the elastic material.

In one embodiment, the elastic material is one of an intestinal tissueobtained from a mammalian abdomen, a man-made bio-compatible tissue, anda polymeric material. The intestinal tissue can be extracted from apatient who receives the replacement heart valve.

In one embodiment, the plurality of cusps comprises three cusps, whereinthe three cusps are formed substantially parallel to each other andsubstantially apart from each other in 120°, as seen from alongitudinal, central axis of the conduit.

In a further aspect, the present invention relates to a method of makinga heart valve holder or conduit holder usable for mounting a conduitformed with an elastic material. In one embodiment, the method has thesteps of providing a tube with a first end portion and an opposite,second end portion, forming a cut longitudinally on the tube, andforming a plurality of holes on the tube. The tube is made from abio-compatible material. In one embodiment, the tube is made from an atleast partially transparent material. For example, the tube can be madefrom a plastic.

The step of forming the cut longitudinally on the tube has the step offorming the cut substantially extending from the first end to the secondend, or vice versa.

Additionally, the method also includes the step of forming a pluralityof round edges around the first end and the second end, respectively,after the cut is formed.

In one embodiment, the step of forming the plurality of holes on thetube has the step of forming three pairs of holes, respectively, wherethe three pairs of holes are formed substantially parallel to each otherand substantially apart from each other in 120°, as seen from alongitudinal, central axis, A, of the tube.

Furthermore, when a conduit formed with an elastic material is mountedto the heart valve holder or conduit holder, the method further has thesteps of guiding a thread through each of the three pair of holes, andtying two corresponding threads from each side for each of the threepair of holes.

In yet a further aspect, the present invention relates to a heart valveholder or conduit holder made according to the method as disclosedabove.

In one aspect, the present invention relates to a heart valve holder orconduit holder. In one embodiment, the heart valve holder or conduitholder has a tube having a first end portion and an opposite, second endportion, a cut formed longitudinally on the tube, and a plurality ofholes formed on the tube.

In one embodiment, the cut is formed substantially extending from thefirst end to the second end of the tube, or vice versa. The plurality ofholes has three pairs of holes, where the three pairs of holes areformed substantially parallel to each other and substantially apart fromeach other in 120°, as seen from the longitudinal, central axis A of thetube. In operation, a replacement heart valve is mounted to the heartvalve holder, a thread is guided through each of the three pair ofholes, and two corresponding threads from each side for each of thethree pair of holes are tied.

Additionally, a plurality of round edges are formed around the first endand the second end of the tube. The tube is made from a bio-compatiblematerial. In one embodiment, the tube is made from an at least partiallytransparent material. For example, the tube can be made from a plastic.

In another aspect, the present invention relates to a replacement heartvalve device. In one embodiment, the replacement heart valve deviceincludes a heart valve holder or conduit holder formed in the form of acylindrical tube having a first end and an opposite, second end. Thecylindrical tube has a cut formed longitudinally and extendingsubstantially from the first end to the second end of the cylindricaltube, or vice versa. The replacement heart valve device further includesa heart valve comprising a conduit that has a first end portion, anopposite, second end portion, and a plurality of cusps formed axiallyextending inwardly from one of the first and second end portions. In oneembodiment, at least a portion of the conduit is formed with a singlelayer of the elastic material. In another embodiment, at least a portionof the conduit is formed with two layers of the elastic material. Theheart valve is mounted onto the heart valve holder or conduit holder tobe used in an operation. In one embodiment, the conduit is formed with atubular segment of intestinal tissue extracted from a human being oranimal. The heart valve holder or conduit holder is formed with abio-compatible material.

In yet another aspect, the present invention relates to a method ofmaking a replacement heart valve that is implantable to a patient. Inone embodiment, the method includes the steps of providing a conduitthat has a first end portion, an opposite, second end portion, aninterior surface, an exterior surface and a diameter d₁, and a pluralityof cusps formed axially extending inwardly from the first end portion;and providing a stent that has a first end, an opposite, second end, anda body portion defines a cavity, wherein the body portion is formed witha netted structure. The method further includes the steps of receivingthe conduit into the cavity of the stent such that the stent ispositioned between the first end portion and the second end portion ofthe conduit with the first end of the stent closer to the first endportion of the conduit than the second end of the stent to the secondend portion of the conduit; attaching the first end of the stent and thefirst end portion of the conduit to each other; attaching the second endof the stent to the conduit; pulling the second end portion of theconduit inside-out towards to the first end portion of the conduit suchthat the stent is entirely covered by the corresponding portions of theconduit; and attaching the second end portion of the conduit to thefirst end portion of the conduit to each other to form a replacementheart valve.

In one embodiment, the conduit is formed of an elastic material.

In one embodiment, the stent formed with a netted structure is aself-expanding stent.

In one embodiment, the step of attaching the first end of the stent andthe first end portion of the conduit to each other comprises the step ofsuturing them together, wherein the sewing is performed with 7-0 or 6-0prolene.

In one embodiment, the step of attaching the second end of the stent tothe conduit comprises the step of suturing them together, wherein thesewing is performed with 7-0 or 6-0 prolene.

In one embodiment, the step of attaching the second end portion of theconduit to the first end portion of the conduit to each other to form areplacement heart valve comprises the step of suturing them together,wherein the sewing is performed with 7-0 or 6-0 prolene.

The sewing can also be performed with string(s) made from othermaterials.

In a further aspect, the present invention relates to a replacementheart valve implantable in a patient. In one embodiment, the replacementheart valve includes a stent that has a first end, an opposite, secondend, and a body portion defines a cavity, wherein the body portion isformed with a netted structure; a conduit formed with a tubular segmentof an elastic material, wherein the conduit has a first end portion andan opposite, second end portion; and a plurality of cusps formed axiallyextending inwardly from one of the first and second end portions,wherein a portion of the conduit is received in the cavity of the stent,and one of the first end portion and the second end portion of theconduit is pulled inside-out towards to and attached to another of thefirst end portion and the second end portion of the conduit such thatthe stent is entirely covered by the corresponding portions of theconduit.

In one embodiment, the plurality of cusps comprises three cusps formedapart from each other.

In one embodiment, the stent formed with a netted structure is aself-expanding stent.

These and other aspects of the present invention will become apparentfrom the following description of the preferred embodiment taken inconjunction with the following drawings, although variations andmodifications therein may be affected without departing from the spiritand scope of the novel concepts of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate one or more embodiments of theinvention and, together with the written description, serve to explainthe principles of the invention. Wherever possible, the same referencenumbers are used throughout the drawings to refer to the same or likeelements of an embodiment, and wherein:

FIGS. 1A-1D show schematically a replacement heart valve in conjunctionwith a procedure of making same according to one embodiment of thepresent invention: (1A) showing a tubular segment of an elasticmaterial, (1B) showing the tubular segment of the elastic materialhaving a first end portion folded inside out towards to the second endportion to form a new first end portion, (1C) showing the tubularsegment of the elastic material having a plurality of cusps formed atthe new first end portion, and (1D) showing a tubular segment of theelastic material completely inverted inside out to form a replacementheart valve that has a conduit at least partially with a single layer ofthe elastic material.

FIG. 1D1 shows schematically a side view of the replacement heart valvethat has a conduit at least partially with a single layer of the elasticmaterial as shown in FIG. 1D, where three valve cusps are in a closedposition, each with a stitch on its edge.

FIG. 1E shows schematically a replacement heart valve in conjunctionwith a procedure of making same according to another embodiment of thepresent invention, following the steps shown in FIGS. 1A-1D: areplacement heart valve has a conduit at least partially with two layersof the elastic material.

FIGS. 2A-2F show schematically a heart valve holder or conduit holder inconjunction with a procedure of making same according to one embodimentof the present invention, (2A) showing a cylindrical tube, (2B) showingthe cylindrical tube having a longitudinal cut, (2C) showing thecylinder having a plurality of smoothly rounded edges formed at thejunctions of the longitudinal cut and the two end of the cylindricaltube, (2D) and (2E) showing the conduit holder having a plurality ofholes formed in the cylindrical tube, and (2F) showing a top view of theheart valve holder or conduit holder;

FIG. 3 shows schematically a replacement heart valve device according toone embodiment of the present invention; and

FIGS. 4A-4C show images of a replacement heart valve device according toone embodiment of the present invention: (4A) showing a replacementheart valve passing through a conduit holder, (4B) showing each of thefirst and second end portions of the replacement heart valve is foldedinside-out and attached onto a corresponding end portion of the conduitholder, and (4C) showing a perspective view of the replacement heartvalve mounted onto the conduit holder.

FIGS. 5A-5E show schematically a replacement heart valve having a stentsuch as a self-expanding stent in conjunction with a procedure of makingsame according to one embodiment of the present invention: (5A) showinga heart valve conduit made in conjunction with a procedure of makingsame according to one embodiment of the present invention as shown inFIGS. 1A-1D is provided; (5B) showing the heart valve conduit ispartially placed inside a self-expanding stent. The length of theconduit is at least twice as long as that of the stent; (5C) and (5D)showing that the stent is attached to the heart valve conduit at aproper configuration; and (5E) showing that one half of the heart valveconduit outside of the stent is pulled towards to the other end of theheart valve conduit inside-out, and that both ends of the heart valveconduit are attached and sewn to form a replacement heart valve with astent inside.

FIGS. 6A-6C show images of an exemplary replacement heart valve having astent made according to the embodiment of the present invention as shownin FIGS. 5A-5E: (6A) showing a conduit is received through the cavity ofa self-expanding stent 620; (6B) showing one end portion of the conduitis folded inside-out towards another end portion of the conduit toenclose the self-expanding stent therein; and (6C) showing a perspectiveview of the replacement heart valve with a self-expanding stentcontained therein.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is more particularly described in the followingexamples that are intended as illustrative only since numerousmodifications and variations therein will be apparent to those skilledin the art. Various embodiments of the invention are now described indetail. Referring to the drawings, like numbers indicate like componentsthroughout the views. As used in the description herein and throughoutthe claims that follow, the meaning of “a”, “an”, and “the” includesplural reference unless the context clearly dictates otherwise. Also, asused in the description herein and throughout the claims that follow,the meaning of “in” includes “in” and “on” unless the context clearlydictates otherwise. Additionally, some terms used in this specificationare more specifically defined below.

As used herein, “around”, “about” or “approximately” shall generallymean within 20 percent, preferably within 10 percent, and morepreferably within 5 percent of a given value or range. Numericalquantities given herein are approximate, meaning that the term “around”,“about” or “approximately” can be inferred if not expressly stated.

The description will be made as to the embodiments of the presentinvention in conjunction with the accompanying drawings of FIGS. 1-6. Inaccordance with the purposes of this invention, as embodied and broadlydescribed herein, this invention, in one aspect, relates to areplacement heart valve and a method of making same.

Referring first to FIGS. 1A-1D, a procedure/method of making areplacement heart valve is shown according to one embodiment of thepresent invention. The method includes the following steps. At first, atubular segment 100 of an elastic material is obtained from a humanbeings or animal, which is used to make a conduit. Suitable elasticmaterial to practice the present invention can be one of an intestinaltissue obtained from a mammalian abdomen, a man-made bio-compatibletissue, and a polymeric material. For certainty and to help readerscomprehend the invention, a tubular segment 100 of an intestinal tissueis chosen as an exemplary example. As shown in FIG. 1A, the tubularsegment 100 has a first end portion 102 and an opposite, second endportion 104, an interior surface 101, an exterior surface 103 and adiameter d₁. The tubular segment 100 of intestinal tissue in oneembodiment is obtained from a mammalian abdomen. For example, theintestinal tissue can be extracted from the patient who receives thereplacement heart valve. Alternatively, the intestinal tissue can beextracted from other human beings or animals. Other types of suitabletissues may also be used to practice the present invention.

Next, the first end portion 102 of the tubular segment 100 is foldedinside-out towards to the second end portion 104 of the tubular segment100 such that the first end 102 of the tubular segment 100 reaches aposition 107 on the exterior surface 103. As a result, the tubularsegment 100 has a new first end 102′ formed therein, as shown in FIG.1B. The first end 102 and the new first end 102′ of the tubular segment100 define a new first end portion 106 with an axial distance d₂ alongthe length of the tubular segment 100, which is substantially equals tod₁, as shown in FIG. 1B.

As shown in FIG. 1C, a plurality of cusps 108 is axially formed on thenew first end portion 164 of the tubular segment 100. In this exemplaryembodiment, three cusps 108 a, 108 b, and 108 c are formed axially alonga new first end portion 106 of the tubular segment 100, by sewinglongitudinally along three lines 108 a, 108 b, and 108 c on the newfirst end portion 104. The cusps 108 a, 108 b, and 108 c are formedsubstantially parallel to each other and substantially apart from eachother. Each cusp is separated from the other cusps by about 120°, viewedfrom a longitudinal, central axis of the tubular segment 100. The sewingcan be performed, for example, with one or more threads of 7-0 or 6-0prolene. Strings made with other proper materials can also be utilized.

Then, the tubular segment 100 is inverted completely inside-out so thatthe exterior surface 103 of the tubular segment 100 and the interiorsurface 101 of the tubular segment 100 exchange their geometricpositions, as shown in FIG. 1D. In relation to the tubular segment 100as shown in FIG. 1B, the second end portion 104 has been invertedinside-out towards to the new first end 102′, such that the second end104 substantially reaches the new first end 102′. Accordingly, theexterior surface 103 and the interior surface 101 of the tubular segment100 shown in FIG. 1B have exchanged their respective geometric positionsto consequently become the interior surface 103 and the exterior surface101, respectively. Dashed reference lines are also shown, which arecorresponding to cusps 108 a, 108 b, and 108 c at the new first end102′. A replacement heart valve that has a conduit at least partiallywith a single layer of intestinal tissue is now formed. Morespecifically, the new first end portion 106 of the conduit has twolayers of intestinal tissue, and the other portions of the conduit has asingle layer of intestinal tissue. When such a replacement heart valvethat has a conduit at least partially with a single layer of intestinaltissue is implanted in a patient's heart, body fluid such as blood willmainly flow through the portions of the conduit that has a single layerof intestinal tissue.

FIG. 1D1 shows schematically a side view of the replacement heart valveshown in FIG. 1D, where three valve cusps 108 a, 108 b, and 108 c are ina closed position, each with a corresponding stitch (109 a, 109 b or 109c) on its edge. In the embodiment, each stitch (109 a, 109 b or 109 c)is positioned substantially on the middle of the edge of a correspondingvalve cusp (108 a, 108 b, or 108 c).

FIG. 1E shows schematically a replacement heart valve in conjunctionwith a procedure of making same according to another embodiment of thepresent invention, following the steps shown in FIGS. 1A-1D: the secondend portion 104 of the tubular segment 100 is folded inside-out towardsto the new first end 102′ such that the second end 104 of the tubularsegment 100 substantially reaches the new first end 102′. As a result, areplacement heart valve has a conduit 100′ at least partially with twolayers of intestinal tissue is formed with the new first end 102′ and anew second end 104′, as shown in FIG. 1E. The new first end 102′ and thenew second end 104′ of the conduit 100′ define an axial distance d₃ thatis no smaller than either of d₁ and d₂. As formed, the portion betweenthe new first end 102′ and the position 107 of the conduit has threelayers of intestinal tissue, and the other portion of the conduit hastwo layers of intestinal tissue. When such a replacement heart valvethat has a conduit at least partially with two layers of intestinaltissue is implanted in a patient's heart, body fluid such as blood willmainly flow through the portions of the conduit that has two layers ofintestinal tissue

Both a replacement heart valve that has a conduit at least partiallywith a single layer of intestinal tissue and a replacement heart valvethat has a conduit at least partially with two layers of intestinaltissue can be mounted to a conduit holder that is described below.

Referring to FIGS. 2A-2E, a procedure/method of making a heart valveholder or conduit holder usable for mounting a replacement heart valveis shown according to one embodiment of the present invention. Themethod includes the step of providing a tube 200 having a first endportion 202 and an opposite, second end portion 204, as shown in FIG.2A. The tube 200 is made from a bio-compatible material. In oneembodiment, the tube 200 is made from an at least partially transparentmaterial. For example, the tube 200 can be made from a transparentplastic.

Then, a cut 210 is formed longitudinally on the tube 200. The cut 210substantially extends from the first end 202 to the second end 204 orvice versa, as show in FIG. 2B. After the cut 210 is formed, round edges212 a, 212 b, 214 a and 214 b are formed around the first end 202 andthe second end 204 of the cut tube 200. Furthermore, a plurality ofholes is formed on the cut tube 200, thereby forming a conduit holder200′. In the embodiment as shown in FIGS. 2D and 2E, the plurality ofholes formed on the cut tube 200 has three pairs of holes 216 a, 216 band 216 c. Each pair of holes is axially aligned. The three pairs ofholes 216 a, 216 b and 216 c are formed substantially parallel to eachother and substantially apart from each other in about 120°, viewed froma longitudinal, central axis A of the conduit holder 200′, as shown inFIG. 2F. These holes are adapted for guiding a thread through each ofthe three pair of holes, where two corresponding threads from each sidefor each of the three pair of holes are tied. Such a heart valve holdercan be utilized to facilitate the medical procedure for implanting areplacement heart valve. Threads of 7-0 or 6-0 prolene can be used topractice the present invention.

FIG. 3 shows schematically a replacement heart valve device 300 having aconduit holder 320 and a conduit 310. The conduit 310 can be one of aconduit at least partially with a single layer of intestinal tissue asshown in FIG. 1D and a conduit at least partially with two layers ofintestinal tissue as shown in FIG. 1E. The conduit holder 320 has aplurality of pairs of holes 316 formed thereon. As assembled, theconduit 310 passes through the conduit holder 320. Each of the first andsecond end portions 312 and 314 of the conduit 310 is folded inside-outand attached onto a corresponding end portion of the conduit holder 320.A total of six threads are placed on the conduit. Three are placed atthe one end of the conduit, at positions 108 a, 108 b, and 108 c in FIG.1C, respectively. Three additional threads are placed at the other endof the conduit, corresponding to positions 108 a, 108 b, and 108 c,respectively. Then, each thread 330 is guided through each pair ofholes, and two corresponding ends of the thread 330 passing through thepair of holes are tied together. Such a replacement heart valve device300 allows a fluid to flow through the conduit 310 from one end of thereplacement heart valve device 300 to the other end of replacement heartvalve device 300, or vice versus, and to allow easy use in a medicalprocedure for a heart valve replacement by medical professionals. Oncethe conduit 310 properly replaces a defective valve of a patient, theconduit holder 320 can be easily disengaged from the conduit 310 andremoved from the patient's heart.

Referring now to FIGS. 5A-5E, a procedure/method of making a replacementheart valve is shown according to yet another aspect of the presentinvention. The method includes the following steps. In one embodiment,as shown in FIG. 5A, a conduit 500 is provided that has a first endportion 502, an opposite, second end portion 504, an interior surface501, an exterior surface 503 and a diameter d₁, and a plurality of cusps508 a, 508 b, 508 c formed axially extending inwardly from the first endportion 502. In one embodiment, the conduit 500 is at least partiallywith a single layer of intestinal tissue as shown in FIG. 1D and formedaccording to the procedure described above in connection with FIGS.1A-1D. Other types of conduit can also be utilized to practice thepresent invention.

As shown in FIG. 5B, a stent 550 is also provided that has a first end552, an opposite, second end 554, and a body portion 551 defines acavity 553, wherein the body portion 551 is formed with a nettedstructure. In one embodiment, the length of the conduit 500 is at leasttwice as long as that of the stent 550. In one embodiment, the stent 550formed with a netted structure is a self-expanding stent. Examples ofself-expanding stents that can be utilized to practice the presentinvention are RX Acculink® Carotid stent with 10.0 mm diameter, ModelNumber 1011342-30, made by Abbott Vascular of Redwood City, Calif.,WALLSTENT® colonic and duodenal Endoprosthesis with 22.0 mm diameter),Model Number M00565640, made by Boston Scientific of Boston, Mass., andPolyflex Airway® stent with 22.0 mm diameter, Model Number M00570320,made by Boston Scientific of Boston, Mass. Other types of self-expandingstents can also be utilized.

In these examples, Acculink® stent is made of nitinol, WALLSTENT® stentis made of metal, and Polyflex Airway® stent is made of silicone. Asfurther described and set forth infra, a replacement heart valve withstent according to the present invention has a unique feature thatsubstantially whole stent, both inside and outside, is covered with anelastic material, here the intestinal tissue, no part of the stent isexposed to body fluid such as blood. Therefore, the material of thestent will not be an issue at least for host- or bio-compatibility.Rather, which stent is chosen will be a matter of ease of use.

Next, as shown in FIG. 5B, the conduit 500 is received into the cavityof the stent 550 such that the stent 550 is positioned between the firstend portion 502 and the second end portion 504 of the conduit 500 withthe first end 552 of the stent 550 closer to the first end portion 502of the conduit 500 than the second end 554 of the stent 550 to thesecond end portion 504 of the conduit 500.

Then, the first end 552 of the stent 550 and the first end portion 502of the conduit 500 are attached to each other. In one embodiment asshown in FIG. 5C, the first end 552 of the stent 550 and the first endportion 502 of the conduit 500 are attached to each other by suturingthem together, wherein the sewing is performed with 7-0 or 6-0 prolene.

For examples, three 6-0 prolene threads 509 a, 509 b and 509 c are usedto suture the first end portion 502 of the conduit 500 through threecorresponding commissures 508 a, 508 b, and 508 c, respectively to thestent 550 through corresponding net structure of the stent 550.

Furthermore, the second end 554 of the stent is attached to the conduit500. In one embodiment, the step of attaching the second end 554 of thestent 550 to the conduit 500 comprises the step of suturing themtogether, wherein the sewing is performed with 7-0 or 6-0 prolene. Forexample, three additional 6-0 prolene threads (only two, 511 a and 511 bare shown) are placed in the corresponding positions of the conduit 500to attach it to the second end 554 of the stent 550, as shown in FIG.5D.

Next, referring now to FIG. 5E, the second end portion 504 of theconduit 500 is pulled inside-out towards to the first end portion 502 ofthe conduit 500 such that the stent 550 is entirely covered by thecorresponding portions of the conduit 500. Then, the second end portion504 of the conduit 500 to the first end portion 502 of the conduit 500are attached to each other to form a replacement heart valve 580. In oneembodiment, the second end portion 504 of the conduit 500 to the firstend portion 502 of the conduit 500 are attached to each other bysuturing them together, wherein the sewing is performed with 7-0 or 6-0prolene. Such a replacement heart valve 580 can be used in apercutaneous heart valve implantation for a patient.

The sewing can also be performed with string(s) made from othermaterials.

In a further aspect, the present invention relates to a replacementheart valve 580 implantable in a patient. In one embodiment, thereplacement heart valve 580 includes a stent 550 that has a first end552, an opposite, second end 554, and a body portion 551 defines acavity 553, wherein the body portion 551 is formed with a nettedstructure. The replacement heart valve 580 further includes a conduit500 formed with a tubular segment of intestinal tissue, wherein theconduit has a first end portion 502 and an opposite, second end portion504, and a plurality of cusps formed axially extending inwardly from oneof the first and second end portions, wherein a portion of the conduit500 is received in the cavity 553 of the stent 550, and one of the firstend portion 502 and the second end portion 504 of the conduit 500 ispulled inside-out towards to and attached to another of the first endportion 502 of the conduit 500 such that the stent 550 is entirelycovered by the corresponding portions of the conduit 500.

In one embodiment, the plurality of cusps comprises three cusps 108 a,108 b and 108 c formed apart from each other.

In one embodiment, the stent 550 formed with a netted structure is aself-expanding stent.

In one embodiment, the conduit 500 is one that is at least partiallywith a single layer of intestinal tissue as shown in FIG. 1D and formedaccording to the procedure described above in connection with FIGS.1A-1D. Other types of conduit can also be utilized to practice thepresent invention.

EXAMPLES OF THE INVENTION

Without intent to limit the scope of the invention, additional exemplarymethods and their related results according to the embodiments of thepresent invention are given below. Note that titles or subtitles may beused in the examples for convenience of a reader, which in no way shouldlimit the scope of the invention.

Each example below is practiced according to at least one aspect of thepresent invention.

Preparing Small Intestine Submucosa (SIS) Material: In this exemplaryembodiment, a section of small intestine (about 30 cm long) washarvested under general anesthesia. The freshly resected section waswashed and mechanically delaminated of the superficial layers of thetunica mucosa and the entire tunica muscularis externa for about 20minutes, while the intestine maintained its cylindrical shape. Theresected section was placed in a container with about 150 ml of dH₂O forabout 4 hours with continuous rocking A complete water change occurredeach hour. The section was then placed in about 300 ml of about 0.01%peracetic acid in sterilized phosphate buffered saline solution withcontinuous rocking for about 20 hours.

Afterwards, the section of small intestine was placed in a containerwith about 200 ml volume of sterilized phosphate buffered salinesolution for about 4.5 hours with continuous rocking A complete solutionchange occurred at least 10 times. Finally, the section was placed in afinal sterile PBS with the container tightly sealed, and keptrefrigerated.

Preparing a Right Ventricular Outflow Tract Conduit: As shown in FIG.1B, the first end 102 of the SIS tubular 100 was folded inside-outtowards the second end 104 of the SIS tubular 100 to form a foldingportion 106 between the first end 102 and a new first end 102′ of theSIS tubular 100. The length, d₂, of the folding portion 106substantially equals to the diameter, d₁, of the SIS tubular 100. Asshown in FIG. 1C, three longitudinal lines 108 a, 108 b and 108 c weresewn with a thread of 7-0 or 6-0 prolene to produce three cuspsaccordingly. Each cusp is apart from the other two cups by 120 degrees.

The SIS tubular 100 was inverted completely inside-out, as shown in FIG.1D. Then, the second end 104 of the SIS tubular 100 was foldedinside-out towards the new first end 102′, thereby forming a conduit100′ having a double-layer wall, as shown in FIG. 1E.

Preparing a Right Ventricular Outflow Tract Conduit with a Valve Holder:In the exemplary embodiment as shown in FIGS. 2A-2E, a thin cylindricaltube 200 with a diameter of about 3 cm and a length of about 3 cm wasutilized to form a conduit holder.

The thin cylindrical tube 200 is made of clear polycarbonate tube lampguard, TGT8 CL, (Lithonia Lighting, Conyers, Ga.).

The cylindrical tube 200 was then cut longitudinally to form a cut 210that extends from one end to the other end of the cylindrical tube 200,as shown in FIG. 2B. Four edges 212 a-212 d at the junctions of the cut210 and the first and second ends 202 and 204 of the cylindrical tube200 were smoothly rounded, as shown in FIG. 2C. Furthermore, three pairsof holes 216 a, 216 b and 216 c were formed on the cylindrical tube 200,with each pair of holes aligned axially and being apart from the othersby about 120° viewed from the longitudinal, central axis A of the tube200, thereby by forming a conduit holder 200′, as shown in FIGS. 2D-2F.The size of each hole was adapted so that a thread/needle of 7-0 or 6-0prolene could pass through therefrom.

Referring back to FIG. 3, the replacement heart valve device 300 has aconduit holder 320 and a conduit 310. The conduit 310 is attached ontothe conduit holder 320, where a thread 330 of 7-0 or 6-0 prolene isguided through each pair of holes of the conduit holder 320. Twocorresponding ends of the thread 330 passing through the pair of holesare tied together.

FIG. 4 shows a replacement heart valve device 400. At first, a conduit410 is passed through the conduit holder 320, as shown in FIG. 4A. Next,each of the first and second end portions 412 and 414 of the conduit 410is folded inside-out and attached onto a corresponding end portion ofthe conduit holder 420. Then, a 7-0 or 6-0 prolene suture was placed onthree commissures on both sides, i.e., a thread 430 of 7-0 or 6-0prolene is guided through each pair of holes, and two corresponding endsof the thread 430 passing through the pair of holes are tied together,as shown in FIGS. 4B and 4C. The replacement heart valve device 400 canbe used in a surgical procedure for replacement of a defective heartvalve of patient.

Preparing a Right Ventricular Outflow Tract Conduit with aself-expanding stent for percutaneous implantation: In the exemplaryembodiment as shown in FIGS. 6A-6C, a self-expanding stent with adiameter of 1.0 cm and a length of about 3 cm was utilized. A rubbercylindrical tube with a diameter of about 1.0 cm and a length of about 6cm was utilized as a conduit candidate to show how a conduit is mountedonto the stent. At first, a conduit 610 is received through the cavityof a self-expanding stent 620, as shown in FIG. 6A. As shown in FIG. 6B,one end portion 614 of the conduit 610 is folded inside-out towardsanother end portion 612 of the conduit 610 to enclose the self-expandingstent 620 therein. Then, as shown in FIG. 6C, the end portion 614 andthe end portion 612 of the conduit are attached together, here tiedtogether through sewing, to form a replacement heart valve 600 that canbe used as, for example, a right ventricular outflow tract conduit witha self-expanding stent for percutaneous implantation.

The foregoing description of the exemplary embodiments of the inventionhas been presented only for the purposes of illustration and descriptionand is not intended to be exhaustive or to limit the invention to theprecise forms disclosed. Many modifications and variations are possiblein light of the above teaching. The embodiments were chosen anddescribed in order to explain the principles of the invention and theirpractical application so as to enable others skilled in the art toutilize the invention and various embodiments and with variousmodifications as are suited to the particular use contemplated.Alternative embodiments will become apparent to those skilled in the artto which the present invention pertains without departing from itsspirit and scope. Accordingly, the scope of the present invention isdefined by the appended claims, the drawings.

1. A method of making a replacement heart valve that is implantable to apatient, comprising the steps of: (a) providing a tubular segment of anelastic material having a first end portion and an opposite, second endportion, an interior surface, an exterior surface and a diameter d₁; (b)folding the first end portion inside-out towards to the second endportion such that the first end of the tubular segment reaches aposition on the exterior surface to form a new first end, wherein thefirst end and the new first end define a new first end portion with anaxial distance d₂ that is substantially equals to d₁; (c) forming aplurality of cusps on axially and extending inwardly from the new firstend portion; and (d) inverting the tubular segment inside-out so thatthe exterior surface of the tubular segment and the interior surface ofthe tubular segment exchange their geometric positions to form a conduitat least partially with a single layer of intestinal tissue.
 2. Themethod of claim 1, wherein the elastic material is one of an intestinaltissue obtained from a mammalian abdomen, a man-made bio-compatibletissue, and a polymeric material.
 3. The method of claim 2, wherein theintestinal tissue is extracted from the patient who receives thereplacement heart valve.
 4. The method of claim 1, wherein the step offorming a plurality of cusps on the new first end portion axiallycomprises the step of forming three cusps by sewing along three lines onthe new first end portion longitudinally.
 5. The method of claim 4,wherein the three cusps are formed substantially parallel to each otherand substantially apart from each other in about 120°, as seen from alongitudinal, central axis of the tubular segment.
 6. The method ofclaim 4, wherein the sewing is performed with 7-0 or 6-0 prolene.
 7. Themethod of claim 1, wherein in operation, the conduit at least partiallywith a single layer of intestinal tissue is mounted onto a conduitholder.
 8. The method of claim 1, further comprising the step of foldingthe second end portion inside-out towards to the new first end such thatthe second end of the tubular segment substantially reaches the newfirst end and a replacement heart valve that has a conduit at leastpartially with two layers of intestinal tissue is formed with the newfirst end and a new second end, wherein the new first end and the newsecond end define an axial distance d₃ that is no smaller than either ofd₁ and d₂.
 9. The method of claim 8, wherein in operation, the conduitat least partially with two layers of intestinal tissue is mounted ontoa conduit holder. 10-41. (canceled)
 42. A method of making a replacementheart valve that is implantable to a patient, comprising the steps of:(a) providing a conduit that has a first end portion, an opposite,second end portion, an interior surface, an exterior surface and adiameter d₁, and a plurality of cusps formed axially on and extendinginwardly from the first end portion; (b) providing a stent that has afirst end, an opposite, second end, and a body portion defines a cavity,wherein the body portion is formed with a netted structure; (c)receiving the conduit into the cavity of the stent such that the stentis positioned between the first end portion and the second end portionof the conduit with the first end of the stent closer to the first endportion of the conduit than the second end of the stent to the secondend portion of the conduit; (d) attaching the first end of the stent andthe first end portion of the conduit to each other; (e) attaching thesecond end of the stent to the conduit; (f) pulling the second endportion of the conduit inside-out towards to the first end portion ofthe conduit such that the stent is entirely covered by the correspondingportions of the conduit; and (g) attaching the second end portion of theconduit to the first end portion of the conduit to each other to form areplacement heart valve.
 43. The method of claim 42, wherein the conduitis formed of an elastic material.
 44. The method of claim 42, whereinthe stent formed with a netted structure is a self-expanding stent. 45.The method of claim 42, wherein the step of attaching the first end ofthe stent and the first end portion of the conduit to each othercomprises the step of suturing them together.
 46. The method of claim45, wherein the sewing is performed with 7-0 or 6-0 prolene.
 47. Themethod of claim 42, wherein the step of attaching the second end of thestent to the conduit comprises the step of suturing them together. 48.The method of claim 47, wherein the sewing is performed with 7-0 or 6-0prolene.
 49. The method of claim 42, wherein the step of attaching thesecond end portion of the conduit to the first end portion of theconduit to each other to form a replacement heart valve comprises thestep of suturing them together.
 50. The method of claim 47, wherein thesewing is performed with 7-0 or 6-0 prolene. 51-53. (canceled)